Witznitz

Now that groundwater levels are no longer controlled for lignite mining purposes around Lake Hainer near Borna, the groundwater level has started rising once more. Some of the areas this groundwater flows through are sloping, so that the decomposed pyrite which exists is causing considerable acidification and the accumulation of sulphate in the lakes of the former mine.

The lake is made up of two disused open pits which are connected by the ground water. They have a total area of 5.67 km² and a volume of approx. 97.9 million m³.

Raising the pH-Value

The objective of this pilot project is to raise the current acid pH-value of 3.0 to 3.5 to a target value of 6.0 to 8.0. This will be achieved by gradually adding 70 m³/h of 1.75% lime water, produced in situ by slaking quick lime. The lime water is fed into the lake from two different points using a sprinkler system. The plant is operated 24 hours a day, is manned and fully automised.